The EPA said the oily sheen has “diminished considerably” but that “degraded sheen” has been spotted “lodged in small, discreet spots” south of the plant.
Local water utilities are continuing stepped-up monitoring and other efforts that they say have prevented the oil from entering filtration plants that treat drinking water for the District and suburbs in Maryland and Northern Virginia. The water utilities put booms in the river last week to divert the oily water from their river intake pipes and are continuing more frequent testing of water in the river, inside the treatment facilities and before the drinking water is sent out to homes and businesses.
A team of a dozen or so investigators from the EPA and state and local environmental agencies have been interviewing business owners along the river to try to track down the source of the oil since it was discovered Nov. 27.
White, the EPA spokeswoman, said Tuesday that NRG notified the EPA and other environmental agencies about the sheen near its Potomac River discharge canal Nov. 27, but that NRG officials said the plant was not the source of the oil. Even so, she said, the EPA continued to consider the power plant as “a potential source.”
“They maintained they were not the source days into the event,” White said.
NRG spokesman David Gaier said the company, which has headquarters in New Jersey and Texas, “had no indication” Nov. 27 that the oil had come from its power plant but notified the EPA “out of an abundance of caution.” He said the company worked with the agencies to try to find the source and put booms in the river to prevent the oil from flowing downstream. The oil release “has been completely stopped,” Gaier said.
The spill was less than 150 gallons, both NRG and EPA officials said.
Gaier said the company didn’t believe the oil came from its plant in part because company officials had heard that the sheen also had been seen upstream from it. White said Tuesday that the EPA did not find any oil upstream from the plant.
Gaier said the company shut down one of its cooling water circulating systems on Nov. 27 “out of an abundance of caution” and shut down two more cooling systems Saturday. He said testing by the Coast Guard determined Monday that the oil in the river matched the oil that the plant uses to lubricate turbines.
Gaier said the company has determined that the spill resulted from “a mechanical failure of some sort” and that the water cooling systems could have caused the leaking oil to reach the river.
“This appears to be a mechanical failure, not a human error of any kind,” Gaier said.
Dean Naujoks, a spokesman for the Potomac Riverkeepers advocacy group, praised the EPA’s investigation, saying, “This sends a strong message that dumping any oil or pollution into the Potomac River is unacceptable.”
Even so, Naujoks said, he questions how the spill happened and when NRG took responsibility for it during an investigation that, so far, has spanned 10 days.
“The longer this went on,” Naujoks said, “the more tax dollars were spent dealing with it and responding to it.”